In many devices, a knob assembly that produces “clicks” during knob rotation is used to provide auditory feedback to a user. In the instance of the elevation and windage assemblies on a rifle scope, the auditory feedback provided by the clicks produced by knob rotation is of particular importance. In many instances, a shooter cannot take his eye from the eyepiece to visually track how much he is turning one of these adjustment knobs, but counts the clicks. At nighttime, it may be too dark for a visual reading, forcing a complete reliance on click counting.
The design of click knobs offers some challenges to the mechanical designer. The current design uses one wheel that turns inside and is pressed against a circular inner surface. Achieving roundness and concentricity sufficient to prevent varying resistance to knob rotation has proven elusive, giving click knobs made according to this design an inconsistent resistance to being turned over the course of a complete rotation, which may elicit a negative response from users.